from collections import defaultdict
from typing import Dict, List, Optional

from backend.app.db.functions.recommendations_functions import (
    bulk_update_plans,
    get_default_plan_ids_for_property,
    get_plans_by_portfolio_id,
    get_plans_by_scenario_ids,
    get_scenarios_by_portfolio_id,
    set_plan_and_scenario_default,
)
from backend.app.db.models.recommendations import PlanModel, ScenarioModel
from backend.app.domain.classes.plan import Plan
from backend.app.domain.classes.scenario import Scenario
from utils.logger import setup_logger

logger = setup_logger()


def process_portfolio(
    portfolio_id: int,
    scenarios_to_consider: Optional[List[int]] = None,
    scenario_priority_order: Optional[List[int]] = None,
) -> None:
    logger.info(f"Processing portfolio {portfolio_id}")

    plans: List[Plan] = _load_plans_for_portfolio(portfolio_id, scenarios_to_consider)

    plans_by_property: Dict[int, List[Plan]] = _group_plans_by_property(plans)

    for property_id, property_plans in plans_by_property.items():

        if not property_plans:
            raise ValueError(f"No plans for property {property_id}")

        cheapest_plan = choose_cheapest_relevant_plan(
            property_plans, scenario_priority_order
        )

        # Unset existing default(s) in case they are outside the plans to consider
        default_plan_ids: List[int] = get_default_plan_ids_for_property(property_id)
        for id in default_plan_ids:
            set_plan_and_scenario_default(id, False)

        _update_default_flags(
            property_plans, cheapest_plan
        )  # TODO: we have already unset existing default(s), so this method can probably be a bit simpler now


def choose_cheapest_relevant_plan(
    plans: List[Plan], scenario_priority_order: Optional[List[int]] = None
) -> Plan:
    scenario_priority_order = scenario_priority_order or []

    eligible_plans: List[Plan] = [plan for plan in plans if plan.is_compliant] or plans
    if not eligible_plans:
        raise ValueError("No plans available to choose from.")

    for plan in eligible_plans:
        if plan.id is None:
            # This should never actually happen, but plan.id is optional to cater
            # for new plans. We are only working with already persisted plans here
            raise ValueError(
                f"All plans must have an ID, but found a plan with no ID: {plan}"
            )

    min_cost: float = min(
        (
            plan.record.cost_of_works
            if plan.record.cost_of_works is not None
            else float("inf")
        )
        for plan in eligible_plans
    )

    cheapest_plans: List[Plan] = [
        plan
        for plan in eligible_plans
        if (plan.record.cost_of_works or float("inf")) == min_cost
    ]

    for priority_scenario_id in scenario_priority_order:
        for plan in cheapest_plans:
            if plan.scenario.id == priority_scenario_id:
                return plan

    return cheapest_plans[0]


def _load_plans_for_portfolio(
    portfolio_id: int, scenarios_to_consider: Optional[List[int]] = None
) -> List[Plan]:

    if scenarios_to_consider:
        if len(scenarios_to_consider) < 2:
            raise ValueError(
                "Cannot run auto categorisation for fewer than 2 scenarios"
            )

        logger.info(f"Getting {len(scenarios_to_consider)} plans")
        plan_models: List[PlanModel] = get_plans_by_scenario_ids(scenarios_to_consider)

    else:
        logger.info(
            f"No list of Plans to consider provided. Getting all Plans for portfolio {portfolio_id}"
        )
        plan_models: List[PlanModel] = get_plans_by_portfolio_id(portfolio_id)

    plans: List[Plan] = []

    scenarios: List[ScenarioModel] = get_scenarios_by_portfolio_id(portfolio_id)

    if not scenarios:
        raise Exception(f"No scenarios found for Portfolio {portfolio_id}")

    for model in plan_models:

        scenario_model = next((s for s in scenarios if s.id == model.scenario_id))
        if not scenario_model:
            logger.info(f"No Scenario associated with Plan of ID {model.id}")
            continue

        plans.append(
            Plan.from_sqlalchemy(model, Scenario.from_sqlalchemy(scenario_model))
        )
        logger.debug(
            f"Successfully mapped plan {model.id} and scenario {scenario_model.id} to domain object"
        )

    logger.debug(f"Got {len(plans)} plans from database")
    return plans


def _group_plans_by_property(plans: List[Plan]) -> Dict[int, List[Plan]]:
    grouped: dict[int, List[Plan]] = defaultdict(list)

    for plan in plans:
        grouped[plan.record.property_id].append(plan)

    return grouped


def _update_default_flags(plans: List[Plan], cheapest_plan: Plan) -> None:
    plans_to_update: List[Plan] = []

    for plan in plans:
        should_be_default: bool = plan.id == cheapest_plan.id
        if plan.record.is_default != should_be_default:
            logger.info(
                f"Setting Plan {plan.id} (Scenario Name: {plan.scenario.record.name}) to is_default: {should_be_default}"
            )
            plan.set_default(should_be_default)
            plans_to_update.append(plan)

    if plans_to_update:
        plan_models: List[PlanModel] = []
        scenario_models: List[ScenarioModel] = []

        for plan in plans_to_update:
            plan_model, scenario_model = plan.to_sqlalchemy()
            plan_models.append(plan_model)
            scenario_models.append(scenario_model)

        bulk_update_plans(plan_models, scenario_models)
        logger.info("Successfully updated Plan default values")

    else:
        logger.info("All plan default values already correct. Not udpating")